N5-L5 Whole Numbers Practice : Factors and Multiples

To achieve learning Outcome of understanding:                     

1. Factors and Multiples

(Part 1) TEACHING(10-15mins)                                             Start Time:                          End Time :

1. Factors and Multiples

(Part2) Core PRACTICE (15-25mins)

Tutor: Please observe and ensure that the student follows the method/step. 

(I) Multiplication Tables (~5mins)                      Start Time:                            

3x2=	4x2=	5x2=	6x2=	7x2=	8x2=	9x2=	12x2=
3x3=	4x3=	5x3=	6x3=	7x3=	8x3=	9x3=	12x3=
3x4=	4x4=	5x4=	6x4=	7x4=	8x4=	9x4=	12x4=
3x5=	4x5=	5x5=	6x5=	7x5=	8x5=	9x5=	12x5=
3x6=	4x6=	5x6=	6x6=	7x6=	8x6=	9x6=	12x6=
3x7=	4x7=	5x7=	6x7=	7x7=	8x7=	9x7=	12x7=
3x8	4x8	5x8	6x8	7x8	8x8	9x8	12x8=
3x9=	4x9=	5x9=	6x9=	7x9=	8x9=	9x9=	12x9=

1.   The factors of 40 are:

2.   The factors of 56 are:

3.   Find a common multiple of 6 and 8.

4.   List the first 8 multiples of 7

5.   List the first 5 multiples of 9

6.         A given number is a multiple of 4. It is between 10 and 20. It is also a factor of 36. What is the number? (2/p2/f) PSLE(2018F)

7.   Use all the digits 7, 8, 9, 1 to form the smallest multiple of an even number.

8*.  List all the common factors of 21 and 45. 

9.   List all the common factors of 24 and 42.

10*.  Use all the digits 6, 5, 2, 8 to form the smallest multiple of 5.

11.  There are 12 pupils in each IT class. There are 7 IT classes in total. How many pupils are in the IT class?

2018 standard

12.      The table below shows a card game. Clement needs to cross out 4 numbers in a row or in a column to win this game. This row or column of 4 numbers needs to have 2 common factors that are greater than 3 but less than 10. What are the 2 common factors? (22/p1/s)

Ans: ________ and __________

                           Total Mark:                /13

Tutor Remark:                                                                                                                      

End Date/Time:                                                        Tutor:                          

Answer Key

1.         1,2,4,5,8,10,20,40

2.         1,2,4,7,8,14,28,56

3.         1, 2

4.         7,14,21,28,35,42,49,56

5.         9,18,27,36,45

6.         12

7.         1798

8.         1,3

9.         1,2,3

10.      2685

11.      84 pupils

12.      7 and 9

N5. Whole Numbers - Factors and Multiples

FACTOR AND MULTIPLES

FACTORS

Factors are numbers that divide exactly into another number.

The factors of 12, for example, are 1, 2, 3, 4, 6 and 12.

=> 12 / 2 = 6 with no remainder, then 12 /6 = 2.

Thus, factors are in pairs and the pairs multiply to be the factors of the number

The factors of 12 are:

1 x 12 = 12    => 1 and 12 are factors of 12.

2 x 6 = 12      => 2 and 6 are factors for 12

3 x 4 = 12      => 3 and 4 are factors for 12.

The factors of 12 are 1, 2, 3, 4, 6 and 12.

All numbers greater than 1 has at least 2 factors :- 1 and the number itself

                        2 = 1 x 2.  1 and 2 are factors of 2

                        3 = 1 x 3.  1 and 3 are factors of 3

                        4 = 1 x 4 and 2 x 2. 1, 2 and 4 are factors of 4.

Example:

Find all the factors of 20.

Method

Step 1: List out the 2 factors of 1 and the number itself

            20 = 1 x 20

Step2:  Multiply from 2 until numbers

            2 x 10 = 20,

            3 – no

            4 x 5 = 20

            6,7,8,9 – no.

            10 found in 2 x 10. – can stop trying.

Step3: Answer

The factors of 20 are 1, 2, 4, 5, 10 and 20

Example:

Find all the factors of 36.

Method

Step 1: List out the 2 factors of 1 and the number itself

            36 = 1 x 36

Step2:  Multiply from 2 until ‘repeated’ factor

            2 x 18 = 36,

            3 x 12 = 36

            4 x 9 – 36

            5 – no

            6 x 6 = 36

            7,8 – no.

            9 found in 4 x 9 (repeated) can stop trying.

Step3: Answer

            The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36.

Common Factors

            Factors of 6 :                                     Factors of 9 :

            1 x 6                                                               1 x 9

            2 x 3                                                               3 x 3

    1 and 3 are common factors of 6 and 9.

Example:

Find the common factors of 24 and 36.

Method

Step1: List out the factors of both numbers

                  24 = 1 x 24                      36 = 1 x 36

                        = 2 x 12                           = 2 x 18

                        = 3 x 8                             = 3 x 12

                        = 4 x 6                             = 4 x 9

                                                                 = 6 x 6

Step2: Circle/Underline the common factors

                  24 = 1 x 24                      36 = 1 x 36

                        = 2 x 12                           = 2 x 18

                        = 3 x 8                             = 3 x 12

                        = 4 x 6                             = 4 x 9

                                                                 = 6 x 6

Step3: Solve

            The common factors are 1, 2, 3, 4, 6 and 12

MULTIPLES

Multiples are extended times tables

The multiples of 2 are all the numbers in the 2 times table:
2, 4, 6, 8, 10, ...
Multiples of 2 always end with a 2, 4, 6, 8 or 0.

Example:

            2478 is a multiple of 2 because it ends with 8.

The multiples of 5 are all the numbers in the 5 times table:
5, 10, 15, 20, 25, ...
Multiples of 5 always end with a 5 or 0.

Example:

            395 is a multiple of 5 because it ends with a 5.

The multiples of 10 are all the numbers in the 10 times table:
10, 20, 30, 40, 50, …
Multiples of 10 always end with a 0.

Example:  

9910 is a multiple of 10 because it ends with a 0.

Common Multiple

First 5 multiples of 4: 4,8,12,16,20

First 5 multiples of 5: 5,10, 15, 20, 25

20 is a multiple of both 4 and 5.

=> 20 is a common multiple of 4 and 5.

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